Multitasking: Gaming while transcoding video
A number of readers over the years have suggested that some sort of real-time multitasking test would be a nice benchmark for multi-core CPUs. That goal has proven to be rather elusive, but we think our new game testing methods may allow us to pull it off. What we did is play some Skyrim, with a 60-second tour around Whiterun, using the same settings as our earlier gaming test. In the background, we had Windows Live Movie Maker transcoding a video from MPEG2 to H.264. Here's a look at the quality of our Skyrim experience while encoding.

Several things happen when we add a background video encoding task to the mix. For one, the Core i7-3960X, with its six cores and 12 threads, reasserts its place at the top of the charts. Although Skyrim alone may not need all of its power, the 3960X better maintains low frame latencies when multitasking. The FX-8150's additional cores come in handy here, as well, as it surpasses the lower-end FX parts. Unfortunately, the 8150 still can't quite match two of the Phenom IIs that preceded it.

The 3960X's latency curve is clearly differentiated from the 3770K's here, while the dual-core i5-655K struggles mightily, falling behind all of the AMD processors, none of which have only two cores.

With most of these CPUs, you can play Skyrim and encode video in the background with relatively little penalty in terms of animation fluidity. We've dialed back our threshold to 50 ms, and as you can see, all of the newer Intel processors avoid serious slowdowns entirely. The AMD chips aren't bad, either, overall. Somewhat surprisingly, the Phenom II X4 980 outperforms the X6 1100T, despite having two fewer cores, presumably thanks to its higher clock speed.